Process of removing metal from slag-surfaced melt



Sept 30, 1969 J. E. cRowE 3,469,740

PROCESS 0F REMOVING METAL FROM SLAG-SURFACED MEM Filed Jan. 24, 1968 I NVENTOR.

JOHN E CROWE United States Patent O 3,469,740 PROCESS F REMOVTNG lViETAL FROM SLAG-SURFACED MELT John E. Crowe, Park Ridge, Ill., assignor to Amsted Industries, Chicago, Ill., a corporation of Delaware Filed Jan. 24, 1968, Ser. No. 700,185 Int. Cl. B67b 7/00 U.S. Cl. 222-1 4 Claims ABSTRACT OF THE DISCLOSURE A slag-free area is provided at the top of a melt in a ladle by bubbling an inert gas upwardly through the melt from a porous plug at the bottom of the ladle, in order to prevent entrapment of the slag in the pouring tube.

This invention relates to the pressure casting of molten or uid materials wherein such materials are forced from a ladle upwardly through a pouring tube into a mold by the application of superatmospheric pressure and more particularly to a process of inserting the pouring tube into the ladle without entrapping slag in the pouring tube.

In the pressure casting of molten metals, it is the common practice to dispose a ladle containing the melt in a sealed tank or pit and provide?. pouring tube cornmunicating with the melt and the casing cavity of a mold. As the molten metal is tapped from the furnace into the ladle, a layer of slag is formed on or carried over to the top of the melt. Before inserting the pouring tube in preparation for the pressure pouring operation, as much of the slag as possible must be removed from the melt by raking in order to prevent slag from entering the pouring tube and subsequently affecting the quality of the casting. In some arrangements of pressure casting equipment, manual removal of the slag by raking or otherwise has been found to be impractical and ineicient, and it is an object of this invention to provide a simple and convenient method for inserting the pouring tube without entrapping slag therein.

Another object is to provide such a method that does not necessitate manual removal of the slag.

Other objects will become apparent from the following description, taken in connection with the accompanying drawing wherein the figure shows a pressure pouring tank and ladle arrangement in vertical cross section, the arrangement being shown also in perspective as slightly tilted forward, in order to better expose the interior thereof.

The arrangement shown generally comprises a ladle containing molten metal 12 and a layer of slag 14 at the top thereof, said ladle being disposed in a fluid-tight tank 16 having a cover 18 which is removable for placement of the ladle therein.

In the pressure casting process, a pouring tube 20 is inserted through an opening 22 in the tank cover 18 downwardly to a point near the bottom of the ladle 10. The top of the pouring tube 20 is then placed into communication with a mold (not shown) and the tank interior is pressurized with air or other suitable uid through an inlet 24 therein.

3,469,740 Patented Sept. 30, 1969 ICC The present invention resides in the provision of a disruptive current which is capable of causing the slag 14 on top of the molten metal 12 to be pushed away from a central portion of the top surface of said metal, leaving a relatively slag free area, indicated at 26, for insertion of the pouring tube 20. The disruptive current mentioned above is best accomplished by means of a central stream of inert gas supplied from a ceramic porous plug 28 located centrally in the bottom of the ladle 10 and connected to a suitable source of inert gas (not shown), such as argon, helium, or the like, by means of a supply line 30.

In operation, after the ladle 10 has been lfilled with molten metal 12 and placed in the tank 16, inert gas is supplied through the porous plug 28, at a pressure sufcient to create a slag free area 26 at the top of the melt. The pouring tube 20 is then inserted into the slag free area 26 without entrapping substantial amounts of the slag 14 at the top of the melt.

Having thus described the invention, what is claimed is:

1. The process of removing slag-free molten metal from a slag-surfaced melt which comprises directing a disruptive current of fluid upwardly through the melt to a limited area of the melt surface so as to disperse slag away from said area, inserting the open inlet end of a pouring tube downwardly through said area into the melt, and withdrawing metal through the tube.

2. The process claimed in claim 1 in which the step of directing a disruptive current of fluid upwardly through the melt comprises bubbling a stream of inert gas from a lower portion of the melt.

3. The process claimed in claim 2 in which the gas is introduced into the melt through a porous plug in the bottom of the container holding the melt.

4. The process of removing slag-free molten metal from a slag-surfaced melt in a ladle contained within a huid-tight tank comprising directing a disruptive current of fluid from an opening in the lower portion of the ladle upwardly through the melt to a limited area of the melt surface so as to disperse slag away from said limited area, inserting the open inlet end of a pouring tube downwardly through the top of the tank and said area into the melt, and then pressurizing the interior of the tank so as to force said metal from the interior of the melt upwardly through the tube.

References Cited UNITED STATES PATENTS 3,314,669 4/ 1967 Knuppel et al 266-34 3,395,750 8/1968 Keene 164-281 FOREIGN PATENTS 927,827 6/ 1963 Great Britain.

ROBERT B. REEVES, Primary Examiner H. S. LANE, Assistant Examiner U.S. Cl. X.R. 

